Scientists Develop World’s Lightest Metal, 100x Lighter than Styrofoam
by Brit Liggett, 11/20/11
This, we assure you, is a real photograph. Researchers at the University of California Irvine have developed a metal micro-lattice that is as strong as solid metal yet 100 times lighter than Styrofoam. The material is constructed from a micro-lattice of nickel phosphorous tubes that is 99.9% air. The tubes are hollow and have walls 1,000 times thinner than a human hair, yet they have the strength of metal with the added benefit of being ultra resistant to strain. Researchers believe this new material could be used to make lightweight batteries that could eventually bring down the weight of green vehicles and increase their efficiency while using less material in the process.
Multidisciplinary team of researchers develop world’s lightest material
UCI mechanical and aerospace engineer plays key role
– Irvine, Calif., November 17, 2011 –
A team of researchers from UC Irvine, HRL Laboratories and the California Institute of Technology have developed the world’s lightest material – with a density of 0.9 mg/cc – about one hundred times lighter than Styrofoam™. Their findings appear in the Nov. 18 issue of Science.
The new material redefines the limits of lightweight materials because of its unique “micro-lattice” cellular architecture. The researchers were able to make a material that consists of 99.99 percent air by designing the 0.01 percent solid at the nanometer, micron and millimeter scales. “The trick is to fabricate a lattice of interconnected hollow tubes with a wall thickness 1,000 times thinner than a human hair,” said lead author Dr. Tobias Schaedler of HRL.
The material’s architecture allows unprecedented mechanical behavior for a metal, including complete recovery from compression exceeding 50 percent strain and extraordinarily high energy absorption.
“Materials actually get stronger as the dimensions are reduced to the nanoscale,” explained UCI mechanical and aerospace engineer Lorenzo Valdevit, UCI’s principal investigator on the project. “Combine this with the possibility of tailoring the architecture of the micro-lattice and you have a unique cellular material.”
Developed for the Defense Advanced Research Projects Agency, the novel material could be used for battery electrodes and acoustic, vibration or shock energy absorption.
William Carter, manager of the architected materials group at HRL, compared the new material to larger, more familiar edifices: “Modern buildings, exemplified by the Eiffel Tower or the Golden Gate Bridge, are incredibly light and weight-efficient by virtue of their architecture. We are revolutionizing lightweight materials by bringing this concept to the nano and micro scales.”
About the University of California, Irvine: Founded in 1965, UCI is a top-ranked university dedicated to research, scholarship and community service. Led by Chancellor Michael Drake since 2005, UCI is among the most dynamic campuses in the University of California system, with nearly 28,000 undergraduate and graduate students, 1,100 faculty and 9,000 staff. Orange County’s largest employer, UCI contributes an annual economic impact of $4.2 billion. For more UCI news, visit www.today.uci.edu
Scientists Invent ‘World’s Lightest’ Material
By Damon Poeter, November 18, 2011
Researchers have created a material that’s so light it can rest comfortably on a dandelion seed head without disturbing the fluffy, delicate structure of the plant. The “ultralight metallic microlattice” invented by scientists at UC Irvine, HRL Laboratories, and Caltech is described in the Nov. 18 issue of Science.
The new material is 100 times lighter than styrofoam, according to reports. The secret to its lightness is a cellular architecture fabricated from hollow tubes that supports a material structure that is in reality 99.99 percent air, according to the research team that built it.
That means the material’s density is less than one-thousandth that of water. And the stuff is pretty resilient as well-researchers said that when squashed to half its height, the material rebounds 98 percent of the way back.
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The material seen resting on a dandelion seed head in the picture above is 90 percent nickel, according to the Times, but Bill Carter, manager of the architected materials group at HRL, told the newspaper that it can be made out of other materials as well.
One UC Irvine researcher involved with the project suggested the ultra-lightweight material might be used for impact protection, and might have applications “in the aerospace industry, acoustic dampening, and maybe some battery applications,” according to the Times.
The material behaves somewhat like a feather when dropped, floating to the ground, Carter told the paper.
“It takes more than 10 seconds, for instance, for the lightest material we’ve made to fall if you drop it from shoulder height,” he said.
World’s Lightest Material: What’s Great About It?
Samita Mohanasundaram, Undergraduate, Harvard College
Imagine holding styrofoam in your hand. It’s lightweight, right?
Now imagine holding something 200 times lighter. Yes, researchers have created the world’s lightest material — the ultralight metallic microlattices.
What exactly is it? Well, it’s actually 99.99% air and .01% nickel phosphorous. The material is made up of connected hollow tubes that contain only a few hundred atoms in their walls.
I recently had the chance to speak with two members from the team, Alan Jacobsen and Bill Carter from HRL Laboratories, who collaborated with researchers from UC Irvine, and CalTech to create the material.
So, what’s their secret? Imagine the Eiffel Tower — it has structural hierarchy. When you step back and look at it, it looks like a truss structure (kind of like a bridge, but a tower). If you zoom into each of the pieces of the tower, those pieces (called struts) are each made of trusses themselves. If you zoom in further, you can see that each strut is also made up of trusses. The Eiffel Tower is essentially a truss of truss of trusses! This is mechanically efficient — the trusses allow you to take out a lot of material that isn’t bearing load in the structural element.
The ultralight metallic microlattices use this same strategy. There is essentially a network of elements and if you zoom in on those elements, you will find that there are tubes. Why tubes instead of rods? Well, if you have two pieces of material that have the same length and same mass, but one’s a rod and the other’s a tube, then the tube is going to be a lot more stiffer to bend than the rod.
Other light materials, such as aerogels, have a random structure. Although this can be beneficial in terms of high surface area and gas flow restriction, these materials have drawbacks in stiffness and strength. Carter mentions that there seems to be a lot of extra material in aerogels that isn’t connected mechanically. Even though aerogels are lightweight, they are poor in stiffness and strength. Researchers in the past have tried to create stronger and stiffer materials, but quickly realized that they needed to sacrifice density. Carter, Jacobsen, and their colleagues were looking at ways you can order materials by using lattice structures. Although the team had to give up some properties with the ultralight metallic microlattices, such as high surface area, they were able to create a lightweight, stiff material.
Why did they choose nickel? It’s because nickel is straightforward to use and easier for fabrication. Carter and Jacobsen state that their lab has also experimented with other materials such as electroplated metals, ceramics, oxides, silica, and other polymers — all these materials can create the hollow tube architecture needed for the microlattice. Carter states, “if we can go to other materials, then we will start getting more interesting properties.” The team also mentioned other interesting methods they could use, such as slurry coating and then burning out polymers.
Now, what we’ve all been waiting for — where can we use this material? Carter and Jacobsen assert that their research is still in the early stages, but they predict there will be applications in many fields, including medicine and energy. The ultralight metallic microlattices can be also used in batteries. It works similar to the way nickel metal hydride batteries are made — we start out with a 3-D electrical conductor that is made of nickel, and then add the active material in the battery, which allows us to make very cheap, very thick electrodes in the battery. On the other hand, lithium ion batteries are promising, but they don’t have the wonderful, 3-D electrode that the nickel metal hydride battery has. Carter notes that one could go down this road with the ultralight metallic microlattices. It would make batteries cheaper to produce, and material that doesn’t contribute to energy storage inside the battery can be minimized.
Why has nobody done this before? It’s because they didn’t have a cost effective method. But, with the microlattices, we now might be able to have better batteries.
The ultralight metallic microlattices also have great use in energy absorption. The future of vehicle technologies is going to be towards lighter weight for fuel efficiency. A lightweight vehicle doesn’t take too much energy to accelerate and decelerate. However, we are looking for materials that will be lightweight without compromising the effectiveness of the vehicle. People want to be in a vehicle that feels stable and comfortable. These microlattices could be useful in application to provide both a structural and energy absorption function.
Jacobsen mentions that the material can be mass-produced at competitive market prices.
Previously, nanotech or nanoscale phenomenon has been limited to particles and thin films. Now with the ultralight metallic microlattices, there’s a new tool that we can use — taking a thin tube and coating on the micromatrix to make a useful, 3-D material.